Since its initial product launch in 2000, VMware has been the company to beat in server virtualization technology when it comes to features, stability, security, and market share. Microsoft's initial attempts with Virtual Server and Virtual PC got the company into the race, but it was a major stretch to compare these products to what VMware was offering at the time. With an inferior product, Microsoft had to grab hold of whatever it could in order to lay claim or take away market share from VMware. In this case, the Redmond giant's best offensive weapon was and has been to offer its solution at a cheaper price.

With the introduction of Microsoft Windows Server 2012 and Hyper-V 3.0, Microsoft is finally on its way to becoming a more feature-rich and stable hypervisor platform, and the company can hold its own in a more apples-to-apples feature comparison with VMware ESX. But even with an improved platform, Microsoft seems intent on hammering away at VMware's costs. This time, Microsoft is going after VMware by using the virtualization giant's own online cost calculator for server virtualization against VMware.

Using VMware's own calculator, Microsoft urges would-be customers to plug the following values in for themselves:

Number of VMs: 100

Virtualization host type: Server B

Network storage type: iSCSI SAN

Compare to vendor: Microsoft

VMware vSphere 5.1 edition: Enterprise Plus

Management deployed on physical or virtual: virtual

Electricity: low

Real estate: low

According to Amy Barzdukas, general manager of server & tools marketing for Microsoft, the above values weren't randomly chosen, but instead represent a common data center virtualization scenario.

The results of this calculation shows that the cost per application to virtualize 100 applications using VMware vSphere 5.1 Enterprise Plus edition is 19 percent higher than with Microsoft Hyper-V and System Center 2012.

Barzdukas said VMware's own calculator confirms that VMware vSphere 5.1 costs more than Windows Server 2012 and System Center 2012 combined. She also said Microsoft isn't just talking about license acquisition costs, but the capital expenditure costs (CAPEX), including power, space, storage, and server hardware costs.

To throw additional fuel on the fire, Barzdukas goes after VMware's calculator claims of having an advantage of being able to run more applications than other hypervisors based on a third-party, VMware-commissioned report from August 2011 that took into account a now older version of Hyper-V. She writes:

We firmly believe you will save far more with Microsoft. According to VMware's calculator, Microsoft's total software cost ($974) is much lower than VMware's ($1,491), but the infrastructure cost ($1,198) is higher than VMware's ($1,083) infrastructure cost. Why is this the case? This happens because the calculator assumes that a VMware ESXi host can run 20% more applications than a Microsoft Windows Server 2012 (Hyper-V) host — an assumption with little credibility or real-life customer evidence.

It took VMware four short days to pen a response on one of its blog sites known as Virtual Reality and to "[set] the record straight one post at a time."